Telephone system



Jan. 16, 1940.

H WUSTENBERG TELEPHONE SYSTEM Filed May 2, 1938 ca E T1 0 ATZ HOUSE HOUSE INVENTOR. HERBERT WUSTENBERG ATTORNEY.

Patented Jan. 16, 1940 UNITED STATES TELEPHONE SYSTEM Herbert Wiistenberg, Berlin, Germany, assignor to Siemens & Halske Aktiengesellschaft, Wernerwerk, Siemensstadt, near Berlin, Germany Application May 2, 1938, Serial No. 205,413 In Germany June 2, 1937 6 Claims.

The invention relates to a circuit arrangement for remote communication, more especially telephone systems in which the call is transferred to a substitute not lying directly on the calling line (exchange line) when the called subscriber does not reply and if the substitute does not reply the call is switched back to the subscriber first called.

With this arrangement in which the subscribers are situated directly on the exchange line,

1 e.-g., by a series system with neighboring stations inside, a substitute called by the transferring line of the principal set first called can switch himself every time on to the exchange line which has not yet been answered by operating his exchange key. As an offset to this with the system in which the substitute is not connected directly to the calling line but for example is connected with the system as an external neighboring set only through a double line there is the disadvantage that a substitute rung up by a transferring of the call has no connection with the calling exchange line which is not yet answeredif he should announce himself in the time between the switching back of the call to the first set called and the recommended carrying on of the call; as a result he is switched rather on to the house line on which no call exists.

According to the invention this disadvantage 30' is avoided in that switching devices which prepare the automatic switching to the calling line by transferring to the substitute, extend this preparation also to switching back the call to the first called subscriber.

The arrangement according to the invention makes it possible for the substitute to .get the calling exchange line by picking up the receiver, when a call is once passed into him so long as the call lasts at all. When there is no answer from the set first called, in an advantageous way switching means become eifective by the first passing on of the call to the substitute, and guide an auxiliary relay preparing the switching in of the substitute, which relay holds right up to the end of the call in a peculiar. circuit independent of the carrying on and/or back switching. In this way the auxiliary relay prepares the circuit of a switching relay arranged in the substituting set in connection with a relay actuated by the calling current, which switching relay then effects the switching in on the calling exchange line by closing the loop at the substitute set. In order to hold the relay energized by the calling current securely switched in during the pause of the second call an electrolytic condenser is provided which is charged during the call and discharges over a second winding of the relay during the calling pause and holds the relay.

An installation of neighboring telephone sets is shown on the attached drawing, in which a principal. set HSt and several neighboring sets are situated on an exchange line AL. Only the outer neighboring set AN I is shown. Only the particulars of this subscribers set necessary for the understanding of the present invention are shown in detail on the drawing,

The switching operations are as follows:

The relay AR in the principal set is excited by a call from the exchange through the calling A. C. over the condenser C3; it switches in the relay B over its contact lar. At the same time the bell W'n. parallel to the relay B is set into operation. While the relays AR and B are periodically switched in and out during the 10 second call, the relay F, excited over the contact 21) by the first action of the relay B, remains in its working position throughout the whole duration of the call. The condenser EC discharges of course, by the opening of contact 32; over the winding II of the relay F, so t-hatthis winding, since the condenser EC is chosen sufficiently large, has a flow of the condenser discharging current maintained through it during the calling pause and so is kept excited. So there is a circuit current for the thermo-relay Thl place over the contact 4 and the contact 5a.

Should there be no answer from the principal set within a definite period, say, for the duration of three calls, the thermo-relay Thl comes to excite and switches the relay Z in over its contact Bthl. This forms a locking circuit over the contact if and its own contact 82, independent of the thermo-relay Thl. Further, through the rotation of the contact 52 the heating circuit of the thermo-relay Thl is broken and so prepares a. circuit for the relay R. The relay R is periodically switched in, in dependence on relay B (in rhythm with the A. C.) and effects over the contacts [01' and I Ir, the sending out of the calling current from the calling A. C. source of the A neighboring set installation to the subscriber of the neighboring set AN l situated further out. The bell of the principal set can be switched off through contact 242 during the transferring of the call to the subscriber; further a circuit for l.

the relay T is formed over the contact l3z and the contact 12 already closed. The relay T excites and holds independently of the contact I32 over its contact I4t until the end of the call. The switching in of the subscriber of the outer taking neighboring set AN l is prepared by the exciting of the relay T.

Should the subscriber of the outerneighboring his earthing key. With the taking up of the receiver the relay A excites of course and switches in the relay VI over. its contact I 521',

which relay closes a circuit for the switching through relay H by its contact Idol, The line HL leading to the housecen'tre (line. selector o.dg|) is switched ofi over the contacts l8h and l9h and the switching through of the exchange line follows over the contacts 20h andZIhto the subscriber of the outer neighboring set AN l with the switching off of the principal set I-ISt.

Should the subscriber of the outer neighboring set ANI not reply within the time of the'pa'ssing of the call the switching back of the call to the principal set results. The thermo-relay Th2 switched in over the contact'ttz, which for example becomes effective a'fter three further calls, short circuits over its contact 25th2 the relay Z so that it releases. The release of the relay Z effects (over contact 52) the switching on of the relay R, calling the neighboring set and with this the end of the call to the outer neighboring set.- The relay T preparing the switching of the outer neighboring set is excited. however. Further, the bell Wh of the principal set is again switched in over contact 242, while the heating circuit of the thermo-relay TM is broken by contact 2552 opening; so that therino-relay TM is switched in again over contact 52.

When now the outer neighboring set replies after the switching back of the call to the principal set, according to the arrangement of the invention the possibility is provided for the subscriber of the outer neighboring. set to be able to 1 switch on directly at thispoint or time to the incoming exchange line; for the relay 'Tpreparing the exciting circuit of the switching relay H is also excited during the switching back of the call to the principal set. So that if the subscrib er of the outer neighboring set now l'ifts' up his receiver, the relays A and Vi come to excite in the way already described and close the circuit for the switching relay H over the'contacts' 77, Ht, IEoI.

If the principal set replies, however, before the outer neighboring set has switcheditself in to receive the call, the switching in'oi' the sub-- sc'riber of the outer neighboring station to the exchange line (e. g. through switching of the relay H) is prevented in a known way which is not described in detail here, F

What is claimed isf 1. In a telephone system, a subscribers station and a line therefor, means for extending a call to said line, timing means associated with'said line operative responsive to the extension of said call thereto, and means controlled by said timing means for preventing the subscriber from receiving said call at said substation for a predetermined interval of time after the call is extended to said line.

2. In a telephone system, a plurality of subscriber substations, means for directing a. call to one of said substations, timing means operative responsive to said call being directed to said one substation, means, controlled by said timing means and effective only if said call is not received at said one substation within a predetermined interval of time to then direct said call to another substation, said call being receivable at said other substation only after said call has been directed thereto. 3.- In a telephone system as claimed in claim 2, a second timing means for controlling said lastnamed" means, saidsecond timing means operativeresponsive to said call being directed to said other substation and effective to cause said call again to be directed to said one substation if said call is not received at said other substation within a predetermined interval of time.

a. In an answering system, a line, a primary and a secondary substation adapted to receive calls thereover, means responsive to a called condition on said line for first signalling the primary substation exclusively for an interval of time, then for signalling the secondary substation for an interval of time, and then for again signal-ling the primary station exclusively, means for preventing the call from being answered at the secondary substation during said first intervalof time, means controlling said last means at the end of said first interval of time to enable the callthereafter to be answered fromv said secondary station irrespective of the substation b ing signalled.

5.,In. an answering system, a line, a primary and a secondary substation adapted to receive calls over said line, means for directing a call to the primary substation, means operated after an interval of time to condition the secondary substation to receive the call, and means for there upon directing said call to said secondary substation and for subsequently redirecting said call to the primary substation if it is not received at said secondary substation within an interval .of time, said second means maintaining said secondary substation conditioned to receive "said call at any time after said first interval of time, whereby the call may be receiv'edat said secondary substation even though same has been redirected to said primary substation.

In a telephone system including a line and a pair of subscriber stations adapted to receive calls thereover, the method of operation which comprises, signalling the stations alternately responsive to a called condition upon said line, preventing the call from being answered at a statien until the same has been signalled, thereby to give preference to the first station signalled, and, once the second station has been signalled, permitting the call thereafter to be answered at said second station regardless of which station is being signalled- HERBERT Wi'ISTENBERG. 

